Best microsd card for Note4 to record 4K video

Happy New Year - I'm looking to buy a micro-sd card for my Note4, and I want to make sure I buy one that can handle recording 4K video without stuttering. Is there a minimum Write speed I should get for my card?

1) There are two companies that make the chips for SD cards - Samsung and SanDisk. Everyone else buys chips from them. Are they getting first quality chips or rejects? I don't know. (But having been in the industry since before the technology was invented, I've heard stories - from people I've learned to believe.) So I'd stick to those two.

2) SanDisk is a great company to work with if you ever do have a problem, which won't be very often. (I still have cards of theirs that have been working for many years. They're too small to be really useful now, but they still work.) They have live chat on their site, and the people at the chat know what they're doing and not only can help you, they seem to want to. I don't own a penny of stock in the company (I don't even know if they're publicly traded), but they're the only cards I buy.

BTW, they do sell refurbs, but not through ebay sellers, so if you see a SanDisk 128GB "factory refurbed: card for $30. I'd pass. (And even the real refurbs carry only a 90 day warranty.) Buy retail, from places like Amazon, Best Buy, Newegg, etc. You pay more, but that 128GB card will still be working when you can't buy anything smaller than 256GB cards. (I still have working 32MB [that's not a typo, it's megabyte] cards that work. that's like a Model T ford that still works and never needed a repair. That's quality.)

3) You want at least a Class 10 card. Ultra (SanDisk's name) is better, Extreme is still better. A faster card won't run better, but when your next phone has a 64 bit 6GHz octacore CPU, the faster card will still run at the phone's full speed.

4) Format the card as exFAT, not FAT32. The largest a file can be on a FAT32 filesystem is 4GB. (It's not a failing, the largest number you can put into 3 digits is 1,000 - 1. The size of the number used for the file size in FAT32 limits the number to 4GB -1.)

A 4k video can easily exceed 4GB, and some apps will actually chop the file into pieces at the 2GB point on a FAT32 filesystem. (Not a problem, because the pieces will play back one after the other, but you still have pieces to copy, not one file.)

On an exFAT card, the largest number is 16 Extabytes (Eib, actually, not EB - the multiplier is 1024, not 1000), and we're not going to see files (or cards) that large for a LONG time. (That's 16 X 103 GB.) The maximum volume size is 128 Petabytes, so the file can actually be larger than a volume (and that will probably change if and when needed unless we're into volume spanning in phones by then).